Model: Monte Carlo
Engine Size: 3.4
There is no power at the compressor. System is charged with freon. All fuses and relay checked good. Light is on at the AC button. Replaced pressure switch near the accumulator with a know good one.
I was about to give up when I noticed the temp gauge isn't working.
If the coolant sensor is bad, will it prevent the compressor from running?
a/c function aborts if engine temp exceeds 255 degf
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
I checked the coolant sensor wires. Only one has voltage. I found on the internet that they are both supposed to have around 5 volts when the key is on. Guessing the problem is in the pcm.
Coolant temp sensor is probably failed, forcing you in to limp home mode. The PCM does all sorts of things with a bad ECT sensor. No gauge means it runs rich, guessing at things from the IAT.
Buy a new sensor.
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.
Just found out ETC was changed recently in attempt to fix temp gauge.
Check sensor ohms and confirm not open circuit, almost all of them will be less ohms hot versus cold. Also check that the pins in the connector are making contact with the sensor.
The wire that has zero volts with sensor connected could be shorted to ground. Check with ohm meter with battery disconnected.
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